/*
 *    Copyright 2006-2020 the original author or authors.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package org.mybatis.generator.internal.util;

import java.util.StringJoiner;
import java.util.stream.Collector;

public interface CustomCollectors {

	/**
	 * Returns a {@code Collector} similar to the standard JDK joining collector,
	 * except that this collector returns an empty string if there are no elements
	 * to collect.
	 *
	 * @param delimiter the delimiter to be used between each element
	 * @param prefix    the sequence of characters to be used at the beginning of
	 *                  the joined result
	 * @param suffix    the sequence of characters to be used at the end of the
	 *                  joined result
	 * @return A {@code Collector} which concatenates CharSequence elements,
	 *         separated by the specified delimiter, in encounter order
	 */
	static Collector<CharSequence, StringJoiner, String> joining(CharSequence delimiter, CharSequence prefix,
			CharSequence suffix) {
		return Collector.of(() -> {
			StringJoiner sj = new StringJoiner(delimiter, prefix, suffix);
			sj.setEmptyValue(""); //$NON-NLS-1$
			return sj;
		}, StringJoiner::add, StringJoiner::merge, StringJoiner::toString);
	}
}
